In the field of print duplication, improvement in the working efficiency of photomechanical processing has long been desired to deal with the present variety of diversified and complicated print forms. In particular, plate assembly and dot-to-dot processes have been attempted in brighter "light-rooms" under safelights to improve the working efficiency of photomechanical processing.
Photographic light-sensitive materials for use under safelights in light-rooms (hereinafter, safelight-sensitive material) used for plate assembly and contact work are generally used for negative/positive image conversion or positive/positive image conversion.
It is desired that by contact exposing light-sensitive material that processed film having original quality letters and/or dot images can be produced. In order to do this, the light-sensitive material must have the following characteristics: (1) the negative/positive conversion or positive/positive conversion of the dot images, line images, and letter images on the original can be carried out in accordance with the dot area, line width, and the letter width, respectively; and (2) the tone of the dot images and the line width of the letter images can be controlled.
Photographic light-sensitive materials that meet these characteristics have been available.
However, in a highly advanced image conversion work known such as reproducing white letter on solid background by contact duplication using known safelight-sensitive material yields inferior images compared to conventional contact work in a dark-room using conventional photographic light-sensitive material.
FIG. 1 shows the formation of images of white letters on a solid background by contact duplication. A transparent or translucent film base (a) (usually, a polyethylene terephthalate film having thickness of about 100 .mu.m); line original (b) having letters or line images formed on it; a transparent or translucent film base (c) (usually, a polyethylene terephthalate film having a thickness of about 100 .mu.m); and a dot original (d) having dot images formed on it are layered and brought into contact with the silver halide emulsion layer of a photographic light-sensitive material (e) prior to exposure.
After exposure, the photographic light-sensitive material is processed to form the transparent parts of the line images formed in the dot image.
When forming images of white letters on a solid background, the negative/positive image conversion is ideally carried out in accordance with the dot area and the image line width of the dot original and the line original, respectively. However, as can be seen in FIG. 1, the dot original (d) is exposed when it is in direct contact with the emulsion layer of the photographic light-sensitive material (e), while the line original (b) is exposed through the intervening film base (c) and the dot original (d).
Because of this arrangement, when sufficient exposure for negative/positive image conversion of the dot original is given, the line width of the transparent parts of the line image is narrowed since the line original is exposed with blurring through the intervening film base (c) and the dot original (d). These factors cause a deterioration in the reproduction quality of white letter on a solid background; a phenomenon that is greatly influenced by the photographic performance of the light-sensitive material and the exposure light source.
Techniques for improving image quality by imagewise exposing photographic light-sensitive material containing a hydrazine derivative and having a .tau. value of at least 10 in light having no wavelengths less than 370 nm are disclosed in JP-A-62-80640 (the term "JP-A" as used herein refers to a "published unexamined Japanese patent application"), JP-A-62-235938, JP-A-62-235939, JP-A-63-104046, JP-A-63-103235, and JP-A-63-296031.
Silver halide photographic materials containing a redox compound releasing a development inhibitor when oxidized are disclosed in JP-A-61-213847, JP-A-64-72410, JP-A-64-72144 and JP-A-64-72139.